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(No Model.)

A. D. MARTIN. HOT AIR FURNACE.

'No. 466,920. Patented Jan. 12, 1892.

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UNITED STATES PATENT OFrrcE.

ALBERT D. MARTIN, OF HAMBURG, NEW YORK, ASSIGNOR OF ONE-HALF TO FISH & KRONENBERG, OF SAME PLACE.

HOT-AIR FURNACE.

SPECIFICATION forming part'of Letters Patent No. 466,920, dated January 12, 1892.

Application filed April 28, 1890. Serial No. 349,771. (No model.)

To all whom; it may concern.-

Be it known that I, ALBERT D. MARTIN, a citizen of the United States, residing at Hamburg, in the county of Erie and State of New York, have invented new and useful Improvements in Hot-Air Furnaces, of which the following is a specification.

This invention relates to that class of hotair furnaces in which an annular chamber or smoke-belt surrounds the fire-pot, which chamber is connected with the combustionchamber in such manner as to receive the products of combustion from the combustionchamber and convey the same to the smokepipe of the furnace.

The object of my invention is to improve the construction of the combustion-chamber and the annular chamber or smoke-belt, so as to obtain a more perfect combustion of the fuel, thereby increasing the temperature and effecting a saving in fuel.

In the accompanying drawings, Figure l is a vertical section of myimproved hot-air furnace. Fig. 2 is a front elevation, partly in section, of the combustion-chamber and aunular smoke-chamber removed from the furnace. Figs. 3 and 4 are horizontal sections in lines 00 :10 and y y, Fig. 1.

Like letters of reference refer to like parts in the several figures.

A represents the inclosiug casing of the furnace; B, the ash-pit; O, the fire-pot resting upon the ash-pit, and c the grate.

D represents the combustion-chamber surmounting the fire-pot and consisting of a cylindrical shell closed at its top by a head d and at its bottom by a ring 01, surroundingthe fire-pot and resting upon an annular rim or shoulder formed at the upper end of the fire-pot. The heads of the combustion-chamber are firmly connected together by vertical tie-bolts d, passing through perforated lugs formed on the heads. The combustion-chamber is preferably provided with an annular row of upright heating pipes or fiues 6, arranged Within the chamber near the wall thereof and secured at their upper ends in openings in the head d and at their lower ends in openings in the ring 61'. These pipes are open at both ends, so that the cold air entering the lower part of the furnace ascends annular passage g, through which a portion of the air rises.

H represents an annular chamber or smokebelt surrounding the fire-pot and separated therefrom by an annular space or passage h, through which the incoming cold air passes before entering the heating-pipes of the combustion-chamber. The annular chamber H is composed of two concentric upright walls or rings "Maud heads 11' 2' The two heads t" 2' are firmly clamped against the ends of the walls 1' by vertical tie-bolts j, and the heads are provided at their inner sides with annular grooves, in which the ends of the walls are confined.

7c represent upright Hues or hollow circular projections arranged on the outer front side of the combustion-chamber on opposite sides of the fire-door f, whereby the annular chamber orsmoke-belt H; is placed in communication with the combu'stion-chamber. The upper ends of these flues are closed and their open lower ends register with openings Z, formed in the upper head of the chamber H, as represented in Fig. 3. Y The lower head of the combustion-chamber is provided on its under side with short tubes ornipples Z, which fit in circular sockets formedflin the upper head of the chamber H, as represented in Fig. 2, so as to form a tight joint. The flues 7c are each provided on theiriuner sides within the combustion-chamber with a longitudinal slot or opening m, which extends from the upper head CZ to the lower head or ring d of the combustion-chamber, as shown.

'n represents the smoke pipe or line, which enters the rear side of the chamber H. The products of combustion pass from the combustion-chamber into the flues k and from the latter into the chamber H. The smoke and gases circulate within the annular chamber or smoke-belt and heat the same, and finally escape through the smoke-pipe. The slots of the flues or conduitsk preferably open rear-i;

the fire-doorfrom passingdirectly into the fines" and compels the same to pass rearwardly to-. ward the sides of the combustion-chamber in' seeking an exit, -thereby retarding their es-i cape and effecting a more perfect combustion. The volume of cold air entering thebottom of the furnace ascends between the fire-pot and the inner Wall of the annular chamber H and is heated on both sides by contact with these parts. It then passes upwardly th rough the heating-pipes,whereby it is further heated, and finally enters the upper part of the easing A, from which latter it is conducted from the furnace by the usualpipes.

0 represents a deflecting ring or flange ar-; ranged at thelower end of the chamber H and extending inwardly to within a short distance: from the fire-pot, so as to leave a narrow cir-;; cular space for the passageof the ascending; cold air. This deflecting ring directs the cold air inwardly against the fire-pot,and.thereby, brings'the bulk of the air into intimate con-i tact with the outer surface of the-fire-pot- Thisdefiecting-ring ispreferably formed on. the lower head 2' of the chamber-H. Bypro-w viding the combustion-chamberlwith-narrow= exit slots or openings 70, extendingfrom top, to bottom of the chamber, the draft is more dif-- fused and equalized in the combustion-chame her than when a single large exit-openi'ngis ar-, ranged at or near the top of the chamber, and the escape of the products of combustion is retarded to a greater extent, thereby producing a more complete combustionand effecting a material saving in fuel. The aggregate'area, of the slots m should about equal the area of the single large exit-opening usually em-. ployed. I

I claim as my invention 1. The combination, with the fire-pot and: the annular chamber or smoke-beltsurrounding the firepot and separated therefrom by an air-passage, of the combustion-chamber formed at its front side with upright lines, each connected at its lower open end with the smoke-belt and provided on its inner side with a slot opening into .the combustionchamber and extending from the upper to the lower head of tliesame, and a smoke-exit pipe connected directly with the rear side of I the smoke-belt, substantially as set forth.

2. The combination, with the firefpot and. the annular chamber or smoke-belt surrounding the fire-pot and separated therefrom by an air-passage, of the combustion-chamber provided at its front side with upright flues, each connected at its lower open end with the smoke-belt and having in its inner side a slot opening into thecombustion-chamber and extendingfroimthe upper to the lower head of the same,air-pipesrarranged within the combustion-chamber and communicating at their lower ends with the air-passage between the smoke-belt and the fire-pot, and an exit-pipe connected directly with the rear side of the substantially as set forth.

4:. The combination, with the fire-pot,the combustion-chamber,and the sinoke-beltsurrounding the fire-pot and separated therefrom by an air space orpassage, of a flue'connecting the smoke-belt with the combustionchamber and an inwardly-projecting flange arranged at the lowerportion of the smokebelt around the fire-.pot,.whereby the ascending cold airri-s directed toward the fire-pot,

substantially-as. set forth.

5. The combination, with the fireepot and '.the combustion-chamber provided with projecting upright flues having longitudinal slotsin their inner sides, whereby they communicate withthe combustion-chamber, of a smoke-belt surrounding the firepot separated therefrom by an air-passage and having its upper head provided with openings which coincide with the lower open ends of saidupright fines and having its lower headformed with an inwardly-extending flangeseparated from the fire-pot by an air-passage andforming a deflector for directing the ascending cold air against the fire-pot, substantially as set forth.

Witness my hand thisZOth clay of March, 1890.

ALBERT D. MARTIN. WVitnesses:

FAYETTE KELLY, NEWTON O. FISH. 

